The correct answer is C. Using the AWS SAM CLI (Serverless Application Model Command Line Interface) allows developers to simulate AWS Lambda environments locally. The steps are as follows: 1) Start the Lambda function locally using the sam local start-lambda command. 2) Generate an S3 event using the sam local generate-event s3 put command. 3) Invoke the Lambda function locally with the generated JSON file using the sam local invoke command. This method has the least operational overhead as it integrates local testing and emulation of the AWS environment efficiently.